1. Field of the Invention
The present invention relates to an item switching method, man-machine interface and sub-handset, and more particularly, to an item switching method, man-machine interface and sub-handset capable of saving required memory space.
2. Description of the Prior Art
A cordless phone is a small coverage telephone system commonly used in daily life and generally composed of a master phone and a portable sub-handset. Since the master phone and the sub-handset exchange signals via air interface, in order to avoid interferences toward other electronic devices or communication products, the prior arts have established related cordless phone communication standards to define operational frequency bands, power, coding, modulations, etc. Digital enhanced cordless telecommunications (DECT) is a widely used cordless phone communication standard, which provides a pico-cell method to achieve clear voice quality without interference.
In addition, in order to increase convenience, DECT-related manufacturers attempt to develop DECT sub-handsets with more functionalities and lower cost, in order to increase product competitivity. However, to satisfy the low cost requires reducing memory implementation, for example, to configure dynamic random access memory to 64K and read-only memory to 512K. In such a situation, with all function equipped, man-machine interface (MMI) development becomes more difficult. The prior arts usually adopt object-oriented programming languages or C language to develop a man-machine interface of a DECT phone, which costs memory to save selection/switching information, and cannot be applied for applications with memory usage limitation. It is necessary to develop a framework or method which reduces memory usage.